Population vs Sampling Frame vs Sample Could someone please explain how the sampling frame is different from population and sample?
I understand that the population is all the sampling unit that match our criteria for the study. And the sample is those select few who participate in the study.
Now, the different answers I have gone through suggests that the sampling frame is from where you draw your sample. But don't we draw our sample from the population?
And if the sampling frame defines the criteria for sampling, then how that criterion is different from the criteria we laid down to define our population.
Hope I am clear with the question!!
Thanks in advance!!
 A: Often, surveys are less than perfect. 
The sampling frame is the set of REACHABLE people whom you are able to survey. 
In addition, the sampling frame may include people that don't belong to the target population. 
from wikipedia:
Missing elements: Some members of the population are not included in the frame.
Foreign elements: The non-members of the population are included in the frame.
Duplicate entries: A member of the population is surveyed more than once.
Groups or clusters: The frame lists clusters instead of individuals.
A: The population is a collection of units you want to analyze. And sampling frame is the collection of units from which you acctually draw a sample. 
As Saketh Malyala wrote in a perfect world sampling frame equals population. However, it's not always easy to draw directly from the population. Imagine your population are people who keep turkeys in your state and now you want to draw a random sample of 100 people from this population. In order to do this you would need a list of all of these people from which you'd randomly draw 100 observations: a sampling frame. However, for such a specific population it's very unlikely that you will find somewhere a complete list of such people. What you are much more likely to find is a list of all farmers from your state and you can use this list to draw a random sample increasing the size of the sample to account for the fact that some of the farmers do not keep turkeys and you will have some missed draws. This is where your sampling frame deviates from the population.  
